The present invention relates to antiperspirant compositions suitable for use in solid stick form. More particularly, it relates to such antiperspirants with improved cosmetic characteristics.
Many solid antiperspirant compositions are described in the chemical and cosmetic literature. In general, there are three types of such antiperspirant stock formulations: compressed powder sticks, gel sticks and wax sticks. While each of these formulation types may have advantages in certain situations, each also has disadvantages. For example, compressed powder sticks are often brittle and hard, and leave a cosmetically-unacceptable dust upon application. Gels may be unstable due to evaporation of alcohol and (more importantly) due to interaction of astringent metal salts with the soaps used in the sticks. Wax-based formulations can also yield cosmetically-unacceptable products due to such factors as hardness, greasiness and stickiness. Nevertheless, the increased stability and antiperspirant efficacy afforded by wax-based formulations has resulted in such sticks being generally preferred for antiperspirant stick products.
The use of a wide variety of materials is described in the literature in order to optimize the cosmetic characteristics of antiperspirant wax-based sticks. For example, U.S. Pat. No. 4,126,679, Davy, et al., issued Nov. 21, 1978, describes antiperspirant sticks containing volatile silicone oils, long-chain fatty alcohols, and a powdered material (such as an antiperspirant active, fumed silica, talc or sodium bicarbonate) for stable sticks with good glide properties. U.S. Pat. No. 4,280,994, Turney, issued July 28, 1981, claims antiperspirant sticks containing volatile silicone, a waxy material and polyethylene glycol, in order to ease application of the composition. British Patent Application No. 2,139,496, Geria, published Nov. 14, 1984, describes the use of a water-soluble emollient in order to avoid the waxy feel of a wax-based antiperspirant stick. European Patent Publication No. 117,070, May, published Aug. 29, 1984, describes wax-based antiperspirant sticks containing certain fatty alcohols in order to increase product stability.
While many stick formulations described in the literature may have certain desirable characteristics, such as acceptable product hardness and stability, or pleasing aesthetics or application characteristics, or good in-use characteristics. Few, if any, sticks provide good performance in all respects. For example, sticks that have good "glide" or other good application characteristics may, however, have poor stability and may be too soft. Such sticks typically also produce undesirable sensations of stickiness on the skin, after application. Conversely, sticks which are dimensionally stable and of adequate hardness may impart a waxy feel and have poor application characteristics. Furthermore, the wax-based sticks described in the literature typically produce high levels of visible residue which is aesthetically unappealing and may leave visible soil on clothing.
It has now been discovered that wax-based antiperspirant sticks containing selected emollients, fillers, and waxes provide good overall cosmetics, both during application to the skin, as well as in-use after application. In particular, the compositions of the present invention afford dry, non-sticky, non-waxy in-use characteristics, with low levels of visible residue, combined with good "glide" and other desirable application characteristics. The sticks of this invention also have good product stability and hardness.